096 reject bare path name mismatch

// ============================================================================
// Test 210_096: MUST_FAIL — a BARE path argument whose last segment puns to a
//   name that is NOT a parameter must be REJECTED at the koru frontend.
//   Bare-side twin of 210_091's legal `echo(v: box.other)`.
//
//   `echo(box.other)` puns to 'other' (last segment), but the only parameter
//   is 'v'. The legal spelling is `echo(v: box.other)`.
//
// CURRENT BEHAVIOR (the bug this pins, worse than 210_094/095): the koru
//   frontend ACCEPTS it and codegen emits MALFORMED Zig referencing an
//   undeclared `v`. The frontend never complains — the harness even reports
//   "compilation SUCCEEDED" — and the only thing that catches it is the Zig
//   compiler at the final executable build:
//     output_emitted.zig: error: use of undeclared identifier 'v'
//   That raw host-level leak is itself a defect (the koru-level wall isn't
//   built here). This test pins BOTH: the missing rejection AND that it must
//   surface as a clean FRONTEND koru error, never as broken emitted Zig.
//   Diagnostic wording is a design call (TBD with the fix).
// ============================================================================

~import std/io

~event echo { v: i32 }
| out i32

~echo => out v

~event get-box {}
| got { v: i32, other: i32 }

~proc get-box|zig { return .{ .got = .{ .v = 7, .other = 11 } }; }

~get-box()
| got box |> echo(box.other)
    | out r |> std/io:print.ln("{{ r:d }}")